Pics of the problem

guys i got the pictures the first one is that the part in the back seat where the second person on the bike holds on, as you can see the previous owner tried to paint it or something and the paint cracked all.
the second is the plastic on the rear brake, not very good quality picture, it is scratched.
and the third is the front light, it has some damages on the side.
if anyone can help me by giving me any advice on how to fix them a little bit , i know that it cant be perfect but just to seem a little better, so i don't have to buy the new parts.

That scuff on the rear brake light doesn't look like it will polish out. A new standard red lens should be pretty cheap on eBay though.

As the rear grab handle is plastic most paints will crack if the handle is used as it will bend and flex. I believe that you can get paints that are used for this kind of thing but I personally couldn't recommend any. Sorry.

For the front light it looks like you need a new surround to get it looking good again. eBay may be your friend again here.

The yellow rear wheel looks good on the bike. A matching front one would look great.